Hello there!
Question: Which of the following is most likely an indication of a chemical change?
Answer Choices:
A. A loud sound when an MP3 player is turned on.
B. A loud sound when someone claps their hands.
C. A loud sound when a starter's pistol is fired at a race.
D. A loud sound when a large object falls to the ground.
Correct Answer:
C. A loud sound when a starter's pistol is fired at a race.
Reasons:
A would not be correct since an MP3 player is a mechanical object and does not mix any substances that create a reaction.
B would not be correct since clapping hands causes a loud sound due to two forces slamming together and causes a disturbance in the air.
D would not be correct since a large object falling to the ground does not indicate any chemical reactions or changes since its merely the result of a mass hitting another mass.
C would be correct since the gunpowder mixes with other substances inside the pistol's chamber and causes and explosion, and explosions are part of a chemical reaction indicators.
Enzymes that eventually break down the surface of bacteria are found in saliva, mucus, and tears, which act as chemical barriers against infection.
Enzymes found in saliva, mucous, as well as tears that degrade bacterial surfaces serve as chemical barriers preventing infection. The stomach's acid as well as the acid in sweat both destroy cellular pathogens, and even the semen contains antibacterial proteins.
There is no chemical and physical barrier offered by macrophages. Instead of acting as a barrier, macrophages target pathogens once they have already entered the body. Physical barriers include mucus as well as stratified squamous epithelium, whereas chemical barriers include saliva and urine.
Therefore, Enzymes that eventually break down the surface of bacteria are found in saliva, mucus, and tears, which act as chemical barriers against infection.
To know more about chemical barriers
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Answer:
first one is a second one is e
Explanation:
Answer:
Explanation:
Hello there!
In this case, for this units conversion problem, it turns out necessary to write the equivalence statement for liters and quarts as follows:
1 qt = 0.946353 L
Thus, the conversion set up turns out to be:
Next, we convert to microliters as follows:
Regards!
Answer : The mass of 7.0 m chain is, 15.12 kg
Explanation :
As we are given that,
The weight of the chain per unit length = 2.16 kg/m
Now we have to determine the mass of chain for 7.0 m length.
As, the mass of 1 m length of chain = 2.16 kg
So, the mass of 7.0 m length of chain = 
= 15.12 kg
Therefore, the mass of 7.0 m chain is, 15.12 kg
